This is the approved USGS MODFLOW 6.2.0 release.

Langevin, C.D., Hughes, J.D., Banta, E.R., Provost, A.M., Niswonger, R.G., and Panday, Sorab, 2020, MODFLOW 6 Modular Hydrologic Model version 6.2.0: U.S. Geological Survey Software Release, 20 October 2020, https://doi.org/10.5066/F76Q1VQV

Visit the USGS "MODFLOW and Related Programs" site for information on MODFLOW 6 and related software: https://water.usgs.gov/ogw/modflow/